Not able to Open Desktop Icons & Folders but able to open Files
Solution 1:
It sounds like the applications to view the files are working, but not the system's filesystem browser. For Gnome, which is what Ubuntu uses, its called "nautilus". If you open a terminal window (Ctrl+Alt+t) and type:
$ nautilus
It should pop up. If it doesn't that's likely broken. (There are other filesystem browsers like "thunar", "pcmanfm", "dolphin" and many more.)
You might have to:
$ sudo tasksel install ubuntu-desktop
Or
$ apt update && apt -f install gnome-session gdm3
(Google these terms and commands for more)
These should also fix a missing "mime-type" or settings file that could be causing your problem.
Scenario two is that you managed to install it with different user permissions, and your current user doesn't have permission to open those.
If this is the case, then:
$ adduser newuser
Set up a password, and log in with the new user, it might work...
Third scenario might be a corrupted disk, or bad memory or just installation from corrupted media, or an interrupted installation, or a botched update. For a botched update, try:
$ apt update && apt upgrade
If it's just the installation best is to reinstall... if it's corrupted disk or memory anything else might stop working at any time. Better check that out first, start by checking the logs:
$ less -S /var/log/syslog
Arrows to scroll, Q to exit. Google anything you don't understand.
Solution 2:
I have the same problem with 18.04. I can open folders this way. click " open with other application". select "Files" and the folder opens.The folder inside opens clicking "open". Another way double click "Files" icon.click "Desktop" All files and folders will appear. click "open" selected folder. it opens.